Good day.

Last Friday I was staking with my ProMark 3 FAST Survey.

For some reason 90.00’ was being subtracted from my elevations. I have not had this problem before. Plus with the number being 90.00 feet it leads me to believe a field has an incorrect number…I was not able to find it.

This was before updating both data collectors.

From the Firmware Release Notes for Surveying Release V2.2 and Fast Survey 2.1.3

“Bugs fixed: Wrong elevation of the reference station”

Was this my problem?

Do you have a geoid model loaded?

There are only a couple places to enter a height, if it was off by exactly 90.00' then you must have the H.I. of the base or rover at 90.00'? You can check either under Base or Rover Configuration.

Brett

Definitely sounds like the geoid isn't loaded.

That’s the first thing I thought of. When I first started I don’t think it was.

I turned off the units and restarted the software and made sure the geoid was loaded. Same results. I deleted the job files and created new ones and made sure the geoid loaded. Same results.

I checked, checked, checked and checked to make sure my control points had the right elevations. They did.

Did you check your raw data to make certain the elevation of your base point wasn't entered incorrectly or the H.I. of your base or rover didn't have any "extra" digits?

What happens if you set up the base at this project again and start from scratch? Same results of a 90' error?

Brett

I worked on this project Saturday and Sunday with no problems. So either the problem went away or the updates fixed it.

“Did you check your raw data to make certain the elevation of your base point wasn't entered incorrectly or the H.I. of your base or rover didn't have any "extra" digits?” Several times. I even deleted the original job and created a new one with a different name.

I think it was one of those days when nothing wanted to go right for me. After encountering the RTK problem I pulled out my Robot. She didn’t want to work. I took everything home and checked over everything and a couple of hours latter went back to work. The 90’ subtraction problem was still there. I was rough grading so I added 90 to all my elevations and made sure I checked into known elevations.

When I was a kid, Mom taught me that if the error you had in balancing your checkbook was divisible by 9, you had transposed two numbers.

Look in the 100s and 10s columns. You may have entered 1450' when you intended to enter 1540'. I learned that from my wife who worked in a bank for 10 years. That did not come to my mind however for this problem.

Thank's Mike for jumping in.